In recent years, digital cameras (image sensing apparatuses) capable of photographing an image by a simple operation and converting the photographed image into digital image data have widely been used. To print an image photographed by this camera and use the print as a photograph, in general, after digital image data of the photographed image is temporarily inputted from the digital camera to a PC (computer) and undergoes image processing by the PC, the processed data is outputted from the PC to a color printer, which prints the data.
To the contrary, there have been recently developed color print systems capable of directly transferring digital image data from a digital camera to a color printer and printing the data without the mediacy of any PC, and so-called photo-direct (PD) printers capable of directly mounting in a color printer a memory card which is mounted in a digital camera and stores a sensed image, and printing the photographed image stored in the memory card.
Particularly when image data is directly transmitted to a printer from a digital camera and the data is printed, since digital cameras vary in specification and operating method from vendor to vendor, photo-direct printers compatible with digital cameras of various vendors have been demanded. Further, in addition to the above digital cameras, such photo-direct printers are considered to receive image data from mobile telephones, PDAs, and the other devices and print the data, and the printers have various functions. Hence, the capabilities of the devices cannot be predicted from each other and thus it is necessary to exchange function information each other.
Further, when image data stored for each image file is acquired from a digital camera, because of a limitation on a memory capacity of a printer, it may not be possible to read the overall image data of the image file and store the image data in the printer. However, in this case, since a data unit for transferring the image data to the printer from the camera is an image file, when the printer does not have a memory capacity enough to store the image file, the image data cannot be transferred.